JP2008017048A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove foreign matter sticking on a cleaning object surface of an imaging unit and not to electrostatically charge the cleaning object surface after the removal. <P>SOLUTION: An imaging device has a cleaning member 11 which can scan in a state of being in contact with a surface of an optical element 201. The cleaning member 11 has conductivity and is grounded through a conduction means during cleaning wherein the cleaning member 11 comes into contact with the surface of the optical element 201 to remove the foreign matter. Consequently, the cleaning object surface after the foreign matter is removed is not electrostatically charged to suppress electrostatic attraction of foreign matter. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image pickup apparatus, and more particularly to an image pickup apparatus provided with a mechanism for removing foreign matter adhering to a surface to be cleaned of an image pickup unit.

  If there is a foreign object such as dust near the focal plane of the camera's taking lens, there is a problem that the shadow of the foreign object is reflected on the solid-state image sensor. Such foreign matters are thought to be caused by dust entering from the outside when the lens is replaced, or by fine abrasion powder such as resin, which is a structural member, due to the operation of the shutter and mirror inside the camera. ing.

  Optical filters such as an infrared cut filter and an optical low-pass filter (hereinafter abbreviated as LPF) disposed in front of the cover glass for protecting the solid-state image sensor and the front surface of the cover, especially dust generated due to such a cause. May get in between. In such a case, the camera had to be disassembled to remove the dust. For this reason, it has been extremely effective to provide a sealed structure so that dust does not enter between the cover glass of the solid-state imaging device and the optical filter.

  However, when dust adheres to the surface of the optical filter that does not face the solid-state image sensor, if the dust is in the vicinity of the focal plane, the dust is reflected in the solid-state image sensor as a shadow. Still remains.

  Therefore, in order to solve such problems, there is one in which the surface of the cover glass of the solid-state imaging device or the outermost surface of the dustproof structure is cleaned with a wiper installed on the shutter (see Patent Document 1). With such a camera configuration, it is possible to remove dust adhering to the cover glass surface of the solid-state imaging device or the outermost surface of the dust-proof structure (for example, the optical filter surface) without removing the lens and without disassembling the camera. Furthermore, there is a method in which an adsorbing cleaning film is slid on the surface of the light receiving element to remove attached dust (see Patent Document 2). As in Patent Document 1, such a camera configuration removes dust attached to the cover glass surface of the solid-state image sensor or the outermost surface of the dust-proof structure (for example, the optical filter surface) without removing the lens and without disassembling the camera. can do.

JP 2003-5254 A JP 2004-172961 A

  However, in the configurations of Patent Document 1 and Patent Document 2, a cleaning member such as a wiper directly contacts a surface to be cleaned. For this reason, there is a problem in that the surface to be cleaned is charged by contact charging, and foreign substances are easily attracted by electrostatic force.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its object is to remove foreign matter adhering in the surface to be cleaned of the imaging unit and to prevent the surface to be cleaned from being removed from being charged. An imaging device is provided.

  In order to achieve the above object, an imaging apparatus according to the present invention is in contact with an imaging element that photoelectrically converts a subject image, an optical element that is disposed upstream of the imaging element in the optical axis direction, and a surface of the optical element. An image pickup apparatus having a scanable cleaning member, wherein at least a part of the cleaning member is electrically conductive, and the cleaning member is connected via a conduction means during cleaning to contact the surface and remove foreign matter. Is connected to the ground.

  According to the present invention, when the foreign matter adhering to the surface to be cleaned of the imaging unit is removed by the cleaning member, the cleaning member is grounded. As a result, the surface to be cleaned after removing the foreign matter can be prevented from being charged, and the foreign matter can be prevented from being attracted by the electrostatic force.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a side sectional view for explaining a schematic configuration of the imaging unit 101, the focal plane shutter 102, and the foreign matter removal mechanism 1.
The imaging unit 101 is mainly configured as follows. In the figure, 201 is an optical low-pass filter, which is held by a holding member 202. Reference numeral 203 denotes a solid-state image sensor, which is housed in a package member 204 and is protected by a cover member 205. Here, the optical low-pass filter 201 is disposed upstream of the solid-state image sensor 203 in the optical axis direction.

  The optical low-pass filter 201 and the cover member 205 are fixed by a seal member 206 for sealing between them. A substrate 207 is connected to the connection terminal 208 of the solid-state image sensor 203 and is mounted with an electrical element that constitutes a control circuit that controls the operation of the imaging apparatus 100. Reference numeral 209 denotes a holding plate for fixing the solid-state image sensor 203.

  The focal plane shutter 102 is mainly configured as follows. Reference numeral 211 denotes a front curtain composed of a plurality of shutter blades 211a, 211b, 211c and 211d, and 212 denotes a rear curtain composed of a plurality of shutter blades. Reference numeral 213 denotes an intermediate plate that divides the drive space of the front curtain 211 and the rear curtain 212 in the focal plane shutter 102. Reference numeral 214 denotes a pressing plate for the rear curtain 212, and at the same time, a pressing plate having an opening at a substantially central portion thereof for imaging. Reference numeral 215 denotes a pressing plate for the front curtain 211, and at the same time its central position for imaging. The cover plate is provided with an opening in the part.

Reference numeral 1 denotes a foreign matter removing mechanism which can be moved in the vertical direction in FIG. 1 by a driving mechanism (not shown). Reference numeral 216 denotes a foreign matter trapping portion provided on the lower side in FIG. 1 in the range in which the foreign matter removal mechanism 1 moves. The foreign matter trapping part 216 is provided with an adhesive part on the side facing the optical low-pass filter 201 (opposing face 216a), so that the foreign matter removed by the foreign matter removing mechanism 1 can be captured. Reference numeral 16 denotes a mask member that presses and fixes the optical low-pass filter 201 to the holding member 202 and restricts the subject light flux. The mask member 16 is formed of metal so as to have conductivity.
One end of the lead wire 31 is connected to the mask member 16, and the other end is connected to the ground of the substrate 207. As a result, the surface of the optical low-pass filter 201 is connected to the same potential as the ground via the mask member 16 and the lead wire 31.

  FIG. 2 is a front perspective view of the foreign matter removing mechanism 1 and the optical low-pass filter 201. The same members as those in FIG. 1 are denoted by the same reference numerals, and the description of the members already described is omitted. In the figure, reference numeral 11 denotes a cleaning member, and a surface of the optical low-pass filter 201 facing the surface is subjected to a flocking process. 12 is a guide shaft, 13 is a lead screw, and the guide shaft 12 and the lead screw 13 are fixed in parallel. Reference numeral 14 denotes a base to which the cleaning member 11 is attached. The base 14 is provided with a hole for fitting with the guide shaft 12 and a screw hole for screwing with the lead screw 13. When the lead screw 13 is rotated by a motor (not shown), the lead screw 13 moves in a direction regulated by the guide shaft 12 (in FIG. 2, the vertical direction (see arrow B)). Reference numeral 15 denotes a holding member 202 that is fixed to the holding member 202 and regulates the distance between the tip of the cleaning member 11 (left side in FIG. 2) and the surface of the optical low-pass filter 201 opposite to the solid-state image sensor 203 (surface to be cleaned). It is a board. The pressing plate 15 has conductivity.

  The foreign matter removing mechanism 1 includes a cleaning member 11, a guide shaft 12, a lead screw 13, a base 14, and a pressing plate 15. As shown in FIG. 2, the mask member 16 is configured to hold the left and right ends of the optical low-pass filter 201 and fix it on the upper and lower surfaces of the holding member 202.

  FIG. 3 is a diagram showing the configuration of the cleaning member 11. In the figure, reference numeral 17 denotes a substantially band-shaped metal plate supported in a cantilever manner by the base 14 and is horizontally mounted so as to maintain a predetermined distance from the surface to be cleaned of the optical low-pass filter 201. A conductive adhesive 18 is applied to the metal plate 17 (base), and electrostatically implanted fibers 19 (foot portions) are fixed substantially vertically. In addition, the fibers 19 are a mixture of conductive fibers 19a and insulating fibers 19b at a predetermined ratio (here, the ratio of the conductive fibers 19a is approximately 10%).

  Here, the reason why all the fibers 19 are not the conductive fibers 19a will be described. In order to manufacture a flocked product using the electrostatic flocking method, it is necessary to leave a substrate coated with an adhesive in a uniform electric field and to disperse fibers using electrostatic force. Therefore, the fiber needs to be insulative in order to receive an electrostatic force due to an electric field. In order to plant the conductive fibers 19a by this method, the conductive fibers 19a are scattered / adhered in a state of being temporarily fixed to the insulating fibers 19b with an adhesive member having an appropriate adhesive force, and then the temporary fixing is removed. Just plant it. If it does in this way, the conductive fiber 19a can be planted using the apparatus conventionally used as it is.

  As described above, since the metal plate 17, the adhesive 18, and the conductive fiber 19a are conductive, the conductive fiber 19a and the metal plate 17 are electrically connected.

  4 is a sectional view taken along line A in FIG. 2 and viewed from below in FIG. As shown in FIG. 4, the fiber 19 scans in the direction perpendicular to the paper surface in FIG. 4 while contacting the optical low-pass filter 201. Further, the pressing plate 15 is connected to the ground portion of the camera via the ground wire 22, and the protruding portion 15 a of the pressing plate 15 is in contact with the cleaning member 11. Here, the pressing member functions as a conduction means for grounding the cleaning member 11.

  FIG. 5 is a view showing a state of the surface of the optical low-pass filter 201 while scanning the cleaning member 11. In the figure, reference numeral 20 denotes a foreign substance. As shown in FIG. 4, the cleaning member 11 scans downward in FIG. 5 while the fiber 19 is in contact with the optical low-pass filter 201. Therefore, the foreign matter 20a adhering to the optical low-pass filter 201 is captured by the fiber 19 (foreign matter 20b) or removed. In this case, since contact charging occurs when the substances come into contact with each other, a charge 21 is generated at the portion where the fibers 19 are in contact. When the electric charge 21 stays in the optical low-pass filter 201, the optical low-pass filter 201 is in a charged state, and as it is, foreign matter floating inside the camera is attracted to the optical low-pass filter 201.

  Therefore, in the present invention, at least a part of the fibers 19 are the conductive fibers 19a, and the adhesive 18 and the metal plate 17 are also conductive, so that the charges 21 can move freely in the cleaning member 11. Furthermore, since the pressing plate 15 in contact with the cleaning member 11 is also conductive, the electric charge 21 can freely move between the cleaning member 11 and the pressing plate 15 or within the pressing plate 15. Here, since the pressing plate 15 is connected to the ground portion of the camera, the charge 21 moves to the ground portion of the camera, and as a result, the charge 21 generated on the surface of the optical low-pass filter 201 can be removed.

  Here, the ground part of the camera will be described. The basic ground of the camera is the negative electrode of the built-in battery. The negative electrode is PGND (power ground), the one that is stabilized for digital signal processing based on PGND is DGND (digital ground), and the one that is further stabilized for analog signal processing is SGND (signal ground) And Thus, it is divided into three and used for signal processing and motor drive. PGND is suitable for removing the electric charge 21, and the presser plate 15 is connected to PGND. Further, not only the presser plate 15 but also the optical low-pass filter 201 is similarly connected to PGND, and is kept at the same potential as the fiber 19.

  A similar effect can be expected by connecting the PGND portion of the camera directly to the metal plate 17. However, since the cleaning member 11 including the metal plate 17 moves at least the distance of the cleaning surface of the optical low-pass filter 201, the member connecting the metal plate 17 and the PGND portion of the camera is limited to a flexible sheet or a lead wire. When the cleaning member 11 scans, it is necessary to secure a space for the flexible sheet or lead wire connected to the PGND portion described above. Therefore, as described in the present embodiment, in terms of space, it can be said that it is more preferable to ground the cleaning member 11 via the fixed pressing plate 15 (connect to PGND).

  In the present embodiment, as a method for grounding the cleaning member 11, the method for removing static electricity via the pressing plate 15 has been described. Further, the same effect can be obtained even when the guide shaft 12 and the base 14 are made of conductive members and the guide shaft 12 is connected to the PGND portion of the camera. Since the guide shaft 12 is also fixed, it is not necessary to secure a space in consideration of the deformation amount of the member connected to the PGND portion of the camera.

  In addition, many methods have been disclosed in which all the fibers 19 are conductive fibers 19a (for example, Japanese Patent Laid-Open Nos. 06-220776, 11-229274, and 2004-330654). Even if the cleaning member 11 is composed of only the conductive fibers 19a using these methods, the effect of the present invention does not change.

  As described above, according to the configuration of the present invention, it is possible to remove foreign matter adhering in the surface to be cleaned of the imaging unit and prevent the surface to be cleaned after being removed from being charged. Accordingly, there is an advantage that a foreign object is always cleaned and removed from the surface to be cleaned of the imaging unit and the state is maintained, and a high-quality captured image is obtained. In this case, the configuration is substantially simplified by ground connection using the constituent members of the foreign matter removing mechanism itself such as the pressing plate 15 or the guide shaft 12.

  The present invention is effective even when mounted on an optical device using an image sensor such as a compact digital camera or video camera. Further, the present invention is based on the premise that the surface to be cleaned is an optical low-pass filter. For example, if there is no optical low-pass filter, the surface to be cleaned is a cover glass disposed in front of the image sensor. Become. Of course, it goes without saying that the present invention is effective even when the surface to be cleaned is the surface of the cover glass.

It is a sectional side view for demonstrating schematic structure of the imaging part, the focal plane shutter, and foreign material removal mechanism in embodiment of this invention. It is a front perspective view of a foreign substance removal mechanism and an optical low-pass filter in an embodiment of the present invention. It is the figure which showed the structure of the cleaning member in embodiment of this invention. FIG. 3 is a cross-sectional view taken along line A in FIG. 2 and viewed from below in FIG. 2. It is the figure which showed the mode of the surface of the optical low-pass filter in operation of the cleaning member in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Foreign material removal mechanism 11 Cleaning member 12 Guide shaft 13 Lead screw 15 Holding plate 17 Metal plate 18 Adhesive 19 Fiber 20 Foreign material 21 Charge 100 Imaging device 101 Imaging unit 102 Focal plane shutter 201 Optical low-pass filter

Claims (8)

An image pickup device having an image pickup device that photoelectrically converts a subject image, an optical element disposed upstream of the image pickup device in the optical axis direction, and a cleaning member that can scan while contacting the surface of the optical element,
At least a part of the cleaning member is conductive, and the cleaning member is grounded via a conduction means during cleaning for removing foreign matter by contacting the surface. Imaging device.   The cleaning member includes a metal plate as a base, an adhesive applied to the metal plate, and a foot portion made of fibers planted on the metal plate using the adhesive, and these members have conductivity. The imaging apparatus according to claim 1, wherein:   The imaging device according to claim 2, wherein the foot portion made of the implanted fiber includes an electrically conductive foot portion and an insulating foot portion.   The conduction means is a pressing member that presses and contacts the metal plate to regulate the position of the cleaning member in order to bring the foot into contact with the surface during scanning of the cleaning member. Item 4. The imaging device according to any one of Items 1 to 3.   The imaging apparatus according to claim 1, wherein the conduction unit is a guide member that supports the cleaning member and guides traveling in a scanning direction.   The said surface is connected to the said ground by the contact member which contacts the said surface other than the said cleaning member contacting at the time of cleaning, and connecting to the said ground. The imaging device described.   2. The power ground is one of a power ground that is a negative electrode of a battery, a digital ground that is stabilized for digital signal processing, and a signal ground that is further stabilized for analog signal processing. The imaging device according to any one of 1 to 6.   The imaging apparatus according to claim 1, further comprising a foreign substance capturing unit that captures and holds the foreign substance removed from the surface of the optical element.

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